1. Field of the Invention
This invention relates generally to liquid supply systems, and more particularly to means for adequately replenishing air which is adsorbed or absorbed by a liquid in a storage vessel pressurized by air.
2. Description of the Prior Art
Air controls for hydropneumatic systems are well known for replenishing air in the water storage tank to make up for that which is absorbed by water eventually used in the system supplied by the tank. Examples of such air controls can be found in United States patents as follows:
______________________________________ Patent No. Issue Date Inventor ______________________________________ 2,183,421 Dec. 12, 1939 Francis E. Brady 2,622,531 Dec. 23, 1952 Francis E. Brady, Jr. 2,709,964 June 7, 1955 Francis E. Brady, Jr. 3,133,501 May 19, 1964 Richard F. Brady 3,805,820 April 23, 1974 Francis E. Brady, Jr. Corbly Leroy Holt Theodore W. Walker ______________________________________
Some other patents describing means for introducing air to a tank are included in the following group of U.S. patents:
______________________________________ Patent No. Issue Date Inventor ______________________________________ 2,578,050 Dec. 11, 1951 Deters 2,793,650 May 28, 1957 Kracht 2,873,758 Feb. 17, 1959 Nielsen 2,971,464 Feb. 14, 1961 Stevens 3,053,435 Sept. 11, 1962 Sanders 3,088,412 May 7, 1963 Good 3,171,351 March 2, 1965 Shelter 3,207,076 Sept. 21, 1965 Morgan 3,259,067 July 5, 1966 Bryan 3,269,318 Aug. 30, 1966 Telford 3,297,236 Jan. 10, 1967 Eckerle 3,318,324 May 9, 1967 Ruth ______________________________________
In this group of patents, it appears that the Sanders patent may be pertinent to my idea of repetitively adding air to a tank if needed during pump operation, but in the Sanders patent it is done by using a single cylinder motor-pump by which the motor drives an air pump to pump air into the tank when the float in the tank indicates a need for air.
In the Telford patent, while there is provision for continuously adding air to the tank if needed while the pump is running, it relies on a pulsating main water supply pump. It states that any means for providing pulses to the air injector will be suitable, but does not elaborate.
In many systems, it is sufficient to add air only once during the pump operating cycle; that is, between the time the pump starts and the pump next starts. Of course, this requires an adequate sized air charging device and such becomes extremely difficult if the particular liquid employed has an extremely great affinity for water. For example, in some systems where oil is used, the absorption rate is extremely high, thus necessitating either large air charging devices, or a number of them operating in parallel, in order to achieve the necessary addition of air to avoid loss of the air cushion in the oil storage vessel. An example of a system in which some improvement is needed is disclosed in U.S. Pat. No. 3,673,614, issued July 4, 1972 to R. W. Claunch of New Orleans, La. There is also needed some means for providing the needed additional air in existing or new systems conveniently, regardless of the type of pump employed, particularly for water systems. The present invention is addressed to solving these various needs.